Router Mode - Disable Firewall / Allow Subnet Communication?

I have an RT-N16 router running DD-WRT SVN revision 21676 successfully. I want to switch it to TomatoUSB (Toastman build 1.28.7502.1 VLAN) to make specific use of the QoS features. This is a simplified layout with both devices having wired clients:

My current setup has a static route in the FVS338 pointing from Subnet 1 to Subnet 2. In DD-WRT I basically just switched from "gateway mode" to "router mode" and disabled the SPI firewall. At that point I could easily communicate between subnets and have internet access.

Is there a good solution to simply allow all traffic when in router mode?